Some different types of machines are known in the prior art either for husking; husking and cleaning; polishing and brightening; cleaning, polishing and brightening; or even for husking, cleaning, polishing and brightening grains in one single operation. However, all the prior art machines have the disadvantage of being designed as machines that exercise an energetic of being the grains with the purpose of removing husk or of polishing at least partially husked grains such as rice, with the purpose of removing the portions of husk remaining on the grains and at the same time polishing and brightening the same.
For instance, U.S. Pat. No. 1,020,377 to Walker, describes a grain cleaning machine which comprises a screen, a rotor concentrically arranged within said screen at a distance therefrom and an axially arranged and radially outwardly extending adjustable retarding blade on the rotor for regulating the movement of the grain and for determining the amount of attrition to which the grain is subjected. This machine, however, although capable of cleaning grains, is designed to exert a rather energetic action on said grains to also remove the hulls thereof and, therefore, is absolutely useless for cleaning and polishing grains without marring their surface.
U.S. Pat. No. 3,960,068 to Salete, describes and claims a machine particularly suitable for partially husking, polishing and whitening rice grains that have been previously husked in a separate machine, which essentially comprises a treatment chamber for grains that includes a cylindrical screen provided with openings designed in an arrangement that provides for a frictioning action on the grains passing therewithin, a rotor provided with a number of radially outwardly extending but axially arranged blades that are adjustable in their radial direction, and a hollow axle for supporting said rotor concentrically arranged within said screen and through which a stream or air is forced to entrain the bran and other impurities released from the grains. The grains are admitted into said chamber under a predetermined pressure and are forced by said rotor and blade to rotate within the treatment chamber and rub against each other and against said screen, which produces a very effective action for removing the husk remaining on the grains and at the same time polishes and whitens or brightens the same. This machine, however, is not capable of exerting a mild action on the grains and cannot be used to clean and polish grains without affecting their surface, because of the rather energetic rubbing action generated between the grains and the screen, effected by the energetic push of the blade of the rotor.
U.S. Pat. No. 4,292,890 to Salete describes a machine which may be regarded as an improvement over the machine of the above discussed patent and also comprises a screen that has axially directed stationary blades in the form of fluted plates arranged around the circumference of the screen, and a rotor having similarly fluted blades that are adjustable in their radial position. Although this machine carries out a more controlled action on the grains, it is nevertheless a machine designed for exercising an energetic action on the grains and also cannot be capable of cleaning and polishing grains without considerably affecting their surface.
U.S. Pat. No. 4,583,455 also to Salete, describes and claims a still more improved rotor and screen assembly for use in the machines described in the above discussed patents, but again it suffers of the same type of disadvantages as the previously described prior art machines, which renders the same incapable of carrying out a sufficiently mild action on the grains so as not to considerable affect their surface.
Some other types of machines for cleaning and polishing grains that supposedly do not considerably affect the surface thereof are known in accordance with the prior art, but said machines are only capable of carrying out one single operation, such as cleaning the grains, or polishing the same, or brightening the same, or removing impurities and lumps therefrom, whereby a considerable amount of machines have to be used for effecting the operations described above, that is, a machine for cleaning the grains, a separate machine for removing lumps therefrom, and a separate machine for polishing the grains, which in turn requires a relatively large investment in equipment, and takes a long time to effect the operations, thus considerably increasing the costs of treatment of certain grains, particularly those in which it is necessary to keep the surface thereof unaffected, such as black of brown beans, lime beams, chickpeas and the like, all of which are grains that must reach the consumer with their surfaces clean and polished but otherwise unaffected in any respect, for the sake of quality.
Up to the present time, that applicant knows, there are no machines extant in the market that may be capable, in one single cycle, of cleaning, polishing and removing impurities and soil lumps from cereal grains that must keep their surfaces otherwise unaffected, whereby for long such a machine has been sought by the workers in the art, without any satisfactory success.